An atomic force microscope (AFM) is a microscope having a resolution at an atomic level under atmospheric pressure, and can easily observe, for example, the fine shape of the surface of a sample (see, for example, Patent Literature 1). In addition, the atomic force microscope can observe not only a conductive material but also an insulating material such as a polymer compound. In those respects, the atomic force microscope is extremely effective as means for observing the surfaces of various samples.
The atomic force microscope observes the shape of the surface of a sample by: scanning the top of the surface with a probe having a tapered tip; and transforming an atomic force felt by the probe into an electric signal. The probe is attached to the tip of a cantilever, and the probe and the surface of the sample are brought into contact with each other by a minute force. Accordingly, when the drift amount of the sample during measurement is large, the following problem arises. An accurate measurement result cannot be obtained.